Biometric authentication is a technology for identifying an individual based on a biometric feature of a person (a vein pattern or the like). In the biometric authentication, a feature data of an individual is registered as a registered data in advance. In an authentication process for determining whether an objective person is an identical person, a feature data obtained by a sensor such as a camera is compared with a registered data. In concrete, a similarity indicating a degree how both data are similar with each other is calculated. When the similarity is more than a given threshold, it is determined that the objective person is the identical person.
The biometric authentication is used in various fields needing identification. For example, the biometric authentication is used in an ATM (Automated Teller Machine), an entering and leaving administration in addition to a logon administration of a personal computer.
Various features in addition to a finger print, a sound and a face can be used as the biometric feature used in the biometric authentication. For example, a vein pattern of a palm or the like can be used. In a vein authentication, a vein image inside of a biometric body is obtained with use of a near-infrared light camera, and the obtained image is used as the biometric feature. The vein authentication uses information inside of a biometric body, and thereby has a merit that a feature is difficult to steal.
Recently, a biometric authentication without contacting such as the vein authentication is focused. Non-contacting authentication is an authentication enabling identification without contacting of a user to an authentication device. The non-contacting authentication reduces a psychological burden from a hygiene viewpoint in a public place. The non-contacting authentication does not need a guide device for fixing a biometric body of a user, and has a merit of downsizing an authentication device.
It is necessary for a user to put his or her hand close to an authentication device with a correct distance. Therefore, it is necessary for a beginner to get used to the non-contacting authentication. And so, Japanese Patent Application Publication No. 2006-042880 discloses a technology in which a guidance image is shown when an imaging of a biometric body is failed.